Challenge-dynamic credential pairs for client/server request validation

ABSTRACT

In an embodiment, a computer system configured to: generate a first challenge credential to be sent to a client computer; render one or more first dynamic-credential instructions, which when executed by the client computer, cause the client computer to generate a first dynamic credential that corresponds to the first challenge credential; modify a first set of instructions, which define one or more original operations, to produce a second set of instructions, wherein the second set of instructions include the first challenge credential and the one or more first dynamic-credential instructions, and which when executed by the client computer, cause the first challenge credential to be included in the one or more requests sent from the client computer; send the second set of instructions to a second computer.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to security techniques applicable to client/server systems, and relates more specifically to techniques for improving the security of client computers interacting with server computers through an intermediary computer using morphing credentials.

BACKGROUND

The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.

Browsers are powerful computer program applications that may request and execute instructions received from a web server to generate complex user interfaces that are presented to a user through one or more devices, such as a monitor or speakers. In response to input from a user, such as a mouse click indicating that the user selected a link, a browser may send a request based on the selected link to the web server. The request may be a request for data and/or include data to be processed by the web server.

A malicious user may use software, often referred to as a “bot”, which imitates a browser by receiving instructions from a web server and generating requests based on those instructions. For example, a bot may receive a web page, and generate a request based on a link defined in the web page, as if the link was selected by a user. Also for example, a bot generate and send a request with data assigned to one or more parameters to simulate a user submitting data to a web server through a browser.

Malicious users may use bots to commit many types of unauthorized acts, crimes or computer fraud, such as content scraping, ratings manipulation, fake account creation, reserving rival goods attacks, ballot stuffing attacks, password snooping, web site scraping attacks, vulnerability assessments, and stack fingerprinting attacks. As a specific example, a malicious user may cause a bot to traverse through pages of a web site and collect private and/or proprietary data, such as who is connected with whom on a particular social networking web site.

Web server administrators may wish to prevent malicious users from attacking the site, while allowing legitimate users to use the site as intended. However, determining which requests are generated by a legitimate user using a web browser and a malicious user using a bot may be difficult.

SUMMARY

The appended claims may serve as a summary of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 illustrates functional units of a web browser.

FIG. 2 illustrates a computer system comprising a browser, an intermediary computer, and a web infrastructure in an example embodiment.

FIG. 3 illustrates detailed view of an intermediary computer in an example embodiment.

FIG. 4 illustrates a process for validating requests from browsers, and filtering out requests from bots, using one or more dynamic credentials, in an example embodiment.

FIG. 5 illustrates a process for updating a credential over time in an example embodiment.

FIG. 6 illustrates a process for generating a seed value and sending the seed value to the client computer to generate one or more new credentials in an example embodiment.

FIG. 7 illustrates a process for validating requests from browsers, and filtering out requests from bots, using one or more dynamic credentials and one or more challenge credentials, in an example embodiment.

FIG. 8 illustrates a computer system upon which an embodiment may be implemented.

While each of the drawing figures illustrates a particular embodiment for purposes of illustrating a clear example, other embodiments may omit, add to, reorder, and/or modify any of the elements shown in the drawing figures. For purposes of illustrating clear examples, one or more figures may be described with reference to one or more other figures, but using the particular arrangement illustrated in the one or more other figures is not required in other embodiments. For example, intermediary computer 230 in FIG. 2 may be described with reference to several components illustrated in FIG. 3 and discussed in detail below, but using the particular arrangement illustrated in FIG. 3 is not required in other embodiments. Furthermore, while the instructions discussed in many example embodiments are HTML, JavaScript, and CSS instructions, in other embodiments, the instructions intercepted and generated may be any other standard and/or proprietary instructions configured to be executed by a client computer.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the present invention.

Embodiments are described herein according to the following outline:

-   -   1.0 General Overview     -   2.0 Differences Between Browsers and Bots         -   2.1 Example Browser Anatomy         -   2.2 Example Bot Anatomy     -   3.0 Network Topology         -   3.1 Web Infrastructure         -   3.2 Intermediary Computer             -   3.2.1 Protocol Client Module             -   3.2.2 Processing Engine             -   3.2.3 Forward Transformer             -   3.2.4 Protocol Server Module             -   3.2.5 Credential Validation Module             -   3.2.6 Reverse Transformer             -   3.2.7 Configurations             -   3.2.8 Storage         -   3.3 Browser     -   4.0 Process Overview         -   4.1 Intercepting Instructions from a Content Server Computer         -   4.2 Modifying Instructions which Causes a Browser to Submit             a Credential with One or More Requests             -   4.2.1 Causing a Browser to Submit a Credential with one                 or more Requests using a Browser Cookie         -   4.3 Rendering a Second Set of Instructions Comprising             Credential-Morphing Instructions         -   4.4 Sending the Modified and Credential-Morphing             Instructions to the Client Computer         -   4.5 Updating the Credential Over Time         -   4.6 Validating a Credential             -   4.6.1 Implied Parameters             -   4.6.2 Express Parameters         -   4.7 Generating a New Credential             -   4.7.1 Generating a First Credential         -   4.8 Sending a New Credential             -   4.8.1 Sending a Seed Value from which the New Credential                 may be Generated         -   4.9 Updating a Credential Over Time         -   4.10 Validating a Request for Data         -   4.11 Performing a Negative Responsive Action         -   4.12 Forwarding the Request to a Server Computer     -   5.0 Process Overview using Challenge-Dynamic Credential Pairs         -   5.1 Generating a Challenge-Dynamic Credential Pair         -   5.2 Updating a Challenge-Dynamic Credential Pair         -   5.3 Determining Whether a Dynamic Credential in a             Challenge-Dynamic Credential Pair is Valid     -   6.0 Implementation Mechanisms—Hardware Overview     -   7.0 Other Aspects of Disclosure

1.0 General Overview

In an embodiment, a computer system comprises: a memory; a processor coupled to the memory; a protocol client module that is coupled to the processor and the memory and configured to intercept a first set of instructions that define one or more original operations, which are configured to cause one or more requests to be sent to the server computer when executed by the client computer; a forward transformer module that is coupled to the processor and the memory and configured to: generate, at the intermediary computer system, a first challenge credential to be sent to the client computer; render one or more first dynamic-credential instructions, which when executed by the client computer, cause the client computer to generate a first dynamic credential that corresponds to the first challenge credential and to include the first dynamic credential in the one or more requests from the client computer; modify the first set of instructions to produce a second set of instructions, wherein the second set of instructions include the first challenge credential and the one or more first dynamic-credential instructions, and which when executed by the client computer, cause the first challenge credential to be included in the one or more requests sent from the client computer; send the second set of instructions to a second computer.

In an embodiment, a data processing method comprises intercepting, from a first computer, a first set of instructions that define one or more original operations, which are configured to cause one or more requests to be sent if executed by a client computer; modifying the first set of instructions to produce a modified set of instructions, which are configured to cause a credential to be included in the one or more requests sent if executed by the client computer; rendering a second set of instructions comprising the modified set of instructions and one or more credential-morphing instructions, wherein the one or more credential-morphing instructions define one or more credential-morphing operations, which are configured to cause the client computer to update the credential over time if executed; sending the second set of instructions to a second computer.

In an embodiment, the method comprises receiving a request for data; performing a negative responsive action in response to determining the request does not include a valid credential. In an embodiment, the method comprises receiving a request for data at a particular time, wherein the request includes the credential and the credential corresponds with one or more parameters; performing a negative responsive action in response to determining that the one or more parameters are not satisfied based, at least in part, on the particular time.

In an embodiment, the method comprises associating the credential with one or more parameters; receiving a first request for a new credential and comprising the credential; determining that the one or more parameters associated with the credential are satisfied, and in response: generating the new credential; associating the new credential with one or more new parameters; sending the new credential to the second computer; receiving a second request, which includes the new credential, for data on the first computer; forwarding at least a portion of the second request to the first computer in response to determining the one or more new parameters associated with the new credential are satisfied.

In an embodiment, the method comprises generating the credential, which comprises one or more encrypted parameters; receiving a first request for a new credential and comprising the credential; decrypting the one or more encrypted parameters to produce one or more decrypted parameters; determining that the one or more decrypted parameters are satisfied, and in response: generating the new credential, which comprises one or more new encrypted parameters; sending the new credential to the second computer; receiving a second request, which includes the new credential, for data from the first computer; decrypting the one or more encrypted parameters to produce one or more new decrypted parameters; forwarding at least a portion of the second request to the first computer in response to determining that the one or more new decrypted parameters are satisfied.

In an embodiment, a method comprises: receiving a one or more instructions that define a first challenge credential, one or more first dynamic-credential instructions, and a first object to be displayed to a user; storing the first challenge credential; executing the one or more first dynamic-credential instructions to produce a first dynamic credential that corresponds to the first challenge credential; causing displaying the object; receiving a first input from the user indicating that the user selected the first object, and in response, sending a first request to a server computer for a first set of data, wherein the first request is based on the object and includes the first challenge credential and the first dynamic credential; receiving, from the server computer, the first set of data and one or more second dynamic-credential instructions, and in response, executing the one or more second dynamic-credential instructions to produce a second dynamic credential that corresponds to the first challenge credential, wherein the one or more second dynamic-credential instructions are different than the one or more first dynamic-credential instructions and the second dynamic credential is different than the first dynamic credential.

2.0 Differences Between Browsers and Bots

A web browser may be a tool through which application programs can provide client computers with content in a dynamic, custom UI. For example, in response to receiving a request for data from a web browser, a web server responds with a set of instructions and/or data. The instructions may define one or more objects that include data and/or other objects. The instructions may also define how the data and/or objects may be presented in a UI to enable human/computer interaction.

In contrast, bots traverse web pages and/or web sites to retrieve data from, and/or submit data to, one or more web servers with little, if any, human/computer interaction. For example, in response to receiving a request for data from a bot, a web server responds with a set of instructions. As discussed above, the instructions may define one or more objects that include data and/or other objects. The instructions may also define how the data and/or objects may be presented in a UI. However, a bot may parse the instructions looking for particular data to store and/or use to make subsequent requests. A bot need not execute the instructions because the bot is built to operate with little, if any, human/computer interaction. The bot may simply look for data by parsing the one or more data structures defined in the instructions. Thus, a bot may be a functionally-limited browser.

A server computer that requires a browser to use one or more parsers and/or execution environments may filter out requests from bots. For purposes of illustrating a clear example, assume a browser includes a JavaScript parser or JavaScript execution engine, and a bot does not include a JavaScript parser or JavaScript execution engine. Also assume that a server computer may include one or more JavaScript instructions in a web page, which if executed, may cause a browser to request, receive, generate, and/or update a dynamic credential. A dynamic credential may be a credential that is updated over time. Accordingly, the browser may parse and execute the one or more JavaScript instructions, which cause the browser to request, receive, generate, and/or update the credential over time and include a valid dynamic credential in a subsequent request.

In contrast, a bot, which does not include a JavaScript parser and/or JavaScript execution environment, may not request, receive, generate, and/or update the dynamic credential over time. Thus, the bot may not include a valid dynamic credential in a subsequent request.

If a server computer receives a request for a web page with a valid dynamic credential from a browser, then the server computer may send the requested web page to the browser. However, if the server computer receives a request without a valid dynamic credential from the bot, then the server computer may perform a negative action, such as terminating the request or ignoring one or more future requests from the bot.

2.1 Example Browser Anatomy

FIG. 1 illustrates functional units of a web browser. Browser 100 may be a browser that is executed on a personal computer, used to communicate with or otherwise conceptually visit a web server, and operated by a user using the personal computer. Browser 100 is communicatively coupled with operating system (“OS”) system application programming interface (“API”) layer 150 and OS frontend API layer 160. Other embodiments may use other protocols, modules, and/or parsers.

Browser 100 comprises protocol module 102, domain name server (“DNS”) module 104, local storage module 106, image parser 108, CSS parser 110, HTML parser 112, JavaScript parser 114, extension execution environment 116, document object model (“DOM”) module 118, and JavaScript execution environment 120. Protocol module 102, DNS module 104, and local storage module 106 may send and/or receive data through OS System API layer 150. For example, protocol module 102 may send and/or receive data over any protocol, such as HTTP, to/from a server computer through OS system API layer 150. Data received through protocol module 102 may reference data sources by one or more domain names. DNS module 104 may resolve the one or more domain names referenced by interfacing with one or more remote domain name servers through OS system API layer 150. Local storage module may store and/or recall data from memory through OS system API layer 150.

Image parser 108, CSS Parser 110, HTML parser 112, and JavaScript parser 114 may parse data received through protocol module 102. HTML parser 112 may parse HTML data. CSS parser 110 may parse CSS data. JavaScript parser 114 may parse JavaScript data. Image parser 108 may parse image data. Each parser may generate and/or update objects in a DOM maintained by DOM module 118.

Browser 100 may comprise sets of program logic implementing one or more programmable engines, such as extension execution environment 116 and JavaScript execution environment 120. Extensions may be written one or more programming languages include JavaScript, Python, Ruby, and/or any other language. Each programmable engine may have access to DOM module 118 and may operate on one or more objects from a DOM maintained by DOM module 118. For example, JavaScript execution environment 120 may execute JavaScript parsed by JavaScript parser 114 and in response, create, update, and/or delete one or more objects managed by DOM module 118, and/or one or more aspects of a UI presenting the one or more objects.

Browser 100 comprises rendering engine 122, interactivity module 124, and user interface 126. Each of the components may cause, through OS frontend API layer 160, one or more objects to be presented to a user using a client computer. Rendering engine 122 may determine how objects are presented to a user. For example, rendering engine 122 may determine the color, shape, orientation, position, and/or any other visual and/or audio attribute of an image, text field, button, and/or any other object defined by a set of received instructions. Furthermore, rendering engine 122 may cause a button to be displayed on a monitor coupled to a client computer through OS frontend API layer 160.

User interface 126 may determine what may be presented to a user. For example, user interface 126 may determine that a “submit” button should be hidden until data has been entered in one or more text fields. After data has been entered in the one or more text fields, user interface 126 may notify rendering engine 122 to render the “submit” button accordingly.

Interactivity module 124 may receive one or more inputs through OS Frontend API layer 160. For example, in response to a user pressing a button on a mouse coupled to a client computer 299, the OS running on the client computer may send a message to interactivity module 124, through OS frontend API layer 160, to indicate that a user pressed a button on a mouse. Interactivity module 124 may determine that a user selected a particular button currently presented on a monitor. Interactively module 124 may notify user interface 126 and/or rendering engine 122 to update to update the UI accordingly.

2.2 Example Bot Anatomy

A bot may include a subset of the modules and/or features included in browser 100. For example, a bot may include protocol module 102, DNS module 104, local storage module 106, and HTML parser 112. A bot need not support a UI; thus, a bot need not include rendering engine 122, interactivity module 124, and user interface 126.

To increase processing time and speed of development, a bot need not include one or more parsers and/or execution environments. For example, a bot may be configured to look for data embedded in a DOM defined in one or more HTML documents. Therefore, a bot may include an HTML parser. However, a bot need not include one or more parsers or execution environments, such as image parser 108, CSS parser 110, JavaScript parser 114, extension execution environment 116, and/or JavaScript execution environment 120.

3.0 Network Topology

FIG. 2 illustrates a computer system comprising a browser, an intermediary computer, and a web infrastructure in an example embodiment. Referring first to FIG. 2, system 200 includes web infrastructure 205, client computer 299, intermediary computer 230, storage 240, and configuration 232 distributed across a plurality of interconnected networks.

A “computer” may be one or more physical computers, virtual computers, and/or computing devices. As an example, a computer may be one or more server computers, cloud-based computers, cloud-based cluster of computers, virtual machine instances or virtual machine computing elements such as virtual processors, storage and memory, data centers, storage devices, desktop computers, laptop computers, mobile devices, and/or any other special-purpose computing devices. Any reference to “a computer” herein may mean one or more computers, unless expressly stated otherwise.

While each of the components listed above is illustrated as if running on a separate, remote computer from each other, one or more of the components listed above may be part of and/or executed on the same computer. For example, intermediary computer 230, configuration 232, storage 240, and/or web infrastructure 205 may be executed on the same computer, local area, and/or wide area network. Additionally or alternatively, intermediary computer 230 may be a proxy server and/or layer for web infrastructure 205. Additionally or alternatively, intermediary computer 230 may be in line between a router and web infrastructure 205, such that intermediary computer 230 may intercept all network data sent to, and/or sent from, web infrastructure 205 over one or more protocols. Additionally or alternatively, intermediary computer 230, and/or one or more modules comprising intermediary computer 230 discussed herein, may be a software layer between, and/or executed on, web infrastructure 205 and/or a component of web infrastructure 205. Additionally or alternatively, intermediary computer 230, and/or one or more modules comprising intermediary computer 230 discussed herein, may be part of a server-side application that responds to requests over one or more standard and/or proprietary protocols, such as HTTP and/or any other protocol.

3.1 Web Infrastructure

Web infrastructure 205 may comprise one or more server computers that receive requests for data from users through one or more computers, such as client computer 299 and/or intermediary computer 230. Web infrastructure 205 may respond by sending data to the browser that sent the request. As illustrated in FIG. 2, the data sent from web infrastructure 205 may include instructions: HTML, JavaScript, and CSS 210. The one or more computers in web infrastructure 205 may, but need not, be owned and/or managed by one or more independent entities and may span across one or more computer networks.

A server computer may be a computer that receives requests for data and responds with data. For example, a web server computer may be an HTTP-based computer that receives HTTP requests and responds with data comprising HTML, CSS, and/or JavaScript instructions. Additionally or alternatively, a server computer may respond with data that references data on other server computers in, and/or outside of, web infrastructure 205.

3.2 Intermediary Computer

Intermediary computer 230 may be an intermediary that may intercept instructions sent from web infrastructure 205, parse and/or execute one or more of the intercepted instructions, modify the intercepted instructions, generate and/or add new instructions, and send the modified and/or new instructions to a client computer. For example, intermediary computer 230 may intercept HTML, JavaScript, and CSS 210, generate modified HTML, JavaScript, and CSS 290, and send modified HTML, JavaScript, and CSS 290 to browser 295. Intermediary computer 230 may intercept a request from browser 295, generate a new and/or modified request, and send the new and/or modified request to web infrastructure 205.

Intermediary computer 230 may be an HTTP or SPDY intermediary that intercepts, parses, executes, and/or processes HTML, JavaScript, and CSS instructions. Additionally or alternatively, intermediary computer 230 may intercept requests for data and/or instructions from a client application, generate a new HTTP request, and send the newly generated HTTP request to one or more HTTP and/or SPDY-based web servers. Additionally or alternatively, intermediary computer 230 may be an intermediary for any other standard and/or proprietary protocol. Furthermore, each of the components discussed herein, which intermediary computer 230 is comprised of, may be configured to perform any of the processes and/or methods discussed herein for any standard and/or proprietary protocol.

Intermediary computer 230 may be a server computer that one or more domain name servers or other elements of the domain name system (“DNS”) identify in DNS records as a destination network address associated with one or more internet domain names. Accordingly, intermediary computer 230 and/or intermediary computer 230 may receive requests sent to the one or more domains from a browser or bot. Based on using DNS to resolve the domain name in a request to a network address, intermediary computer 230 may forward the request, or a modified request, to a server computer in web infrastructure 205, such as original web server computer 302.

In FIG. 2, intermediary computer 230 is programmed to send instructions to, and receive requests from, a particular type of client application: browser 295. However, in an embodiment, intermediary computer 230 may be programmed to send instructions to, receive requests from, and/or open sockets with browsers and/or bots.

FIG. 3 illustrates detailed view of an intermediary computer in an example embodiment. In FIG. 3, intermediary computer 230 comprises protocol client module 332, processing engine 334, forward transformer 336, protocol server module 338, credential validation module 340, and reverse transformer 342. In an embodiment, each of the functional units of intermediary computer 230 may be implemented using any of the techniques further described herein in connection with FIG. 8; for example, the intermediary computer 230 may comprise a general-purpose computer configured with one or more stored programs which when executed cause performing the functions described herein for the intermediary computer, or a special-purpose computer with digital logic that is configured to execute the functions, or digital logic that is used in other computing devices. While the figures include lines that indicate various devices and/or modules being communicatively coupled, each of the computers, devices, modules, storage, and configurations may be communicatively coupled with each other.

Each module illustrated in intermediary computer 230 may be software and/or hardware coupled to a memory and/or one or more processors on one or more computers. Additionally or alternatively, a module may comprise specialized circuitry. For example, a module, such as a protocol client module 332, processing engine 334, forward transformer 336, protocol server module 338, credential validation module 340, and/or reverse transformer 342 may be hardwired and/or persistently programmed to support a set of instructions to, and/or that are useful to, perform the functions discussed herein, such as receiving instructions from web infrastructure 204, processing and/or executing the instructions, modifying the instructions to generate and/or update one or more credentials, sending the modified instructions to a browser or bot on a client computer, receiving requests and determine whether the requests include valid credentials, and/or responding accordingly as discussed in detail herein.

3.2.1 Protocol Client Module

Protocol client module 332 may intercept data over any standard or proprietary protocol. For example, protocol client module 332 may intercept data over HTTP.

3.2.2 Processing Engine

Processing engine 334 may process instructions intercepted by protocol client module 332, which causes processing engine 334 to generate one or more data structures. Processing one or more instructions may comprise parsing and/or executing the one or more instructions. After processing the instructions, processing engine 334 may notify forward transformer 336 to begin rendering instructions based on the one or more data structures created by processing engine 334 that are currently in memory.

Processing engine 334 may make requests for additional data. For example, if instructions received from protocol client module 332 reference additional instructions stored on another web server, then processing engine 334 may request the additional instructions through protocol client module 332.

3.2.3 Forward Transformer

Forward transformer 336 may render a new set of instructions based on the one or more data structures in memory. Additionally or alternatively, forward transformer 336 may operate on the objects created by processing engine 334 and generate one or more credential-morphing instructions, which if executed are configured to cause a browser to request, receive, generate, and/or update one or more dynamic credentials. Forward transformer 336 may store the one or more dynamic credentials and/or data associated with one or more dynamic credentials in storage 240. Forward transformer 336 may operate on objects and/or render instructions based on one or more configurations specified in configuration 232. Forward transformer 336 may send the rendered instructions to one or more client computers through protocol server module 338. Instructions that are programmed and/or configured to generate and/or update a dynamic credential may be referred to herein as dynamic-credential instructions or credential-morphing instructions.

Forward transformer 336 may generate one or more challenge-credential instructions, which if executed are configured to cause a browser to request, receive, generate, and/or update one or more challenge credentials. A challenge credential may be a credential that one or more dynamic credentials correspond to. A challenge credential may be static or dynamic. A challenge-dynamic credential pair is a challenge credential and a dynamic credential, wherein the dynamic credential corresponds to the challenge credential. Forward transformer 336 may store one or more challenge credentials, and/or data indicating which dynamic credentials correspond to which challenge credentials, in storage 240. Forward transformer 336 may send challenge credentials and/or challenge-credential instructions to one or more client computers through protocol server module 338.

3.2.4 Protocol Server Module

Protocol server module 338 may receive the instructions generated by forward transformer 336 and send the generated instructions to client computer 299. Additionally or alternatively, protocol server module 338 may intercept requests from client computer 299 and forward the requests to credential validation module 340.

3.2.5 Credential Validation Module

Credential validation module 340 may receive requests intercepted by protocol server module 338 from browser 295. Credential validation module 340 may validate requests and/or credentials, and forward the requests for one or more pages to reverse transformer 342.

Credential validation module 340 may generate one or more dynamic credentials. For example, forward transformer 336 may render a page and embed a dynamic credential received from credential validation module 340 into the page. Also for example, in response to a request from a client computer for a dynamic credential, credential validation module 340 may generate a new, valid dynamic credential and send the new dynamic credential to the client computer through protocol server module 338.

Credential validation module 340 may generate one or more parameters associated with a dynamic credential. For example, credential validation module 340 may store a credential, a timestamp, and an Internet Protocol (“IP”) address in storage 240. As discussed in detail herein, credential validation module 340 may validate a request with the stored credential based on the timestamp and the IP address associated with the stored credential.

Credential validation module 340 may generate one or more challenge credentials. If credential validation module 340 receives a dynamic credential and a challenge credential, then credential validation module 340 may determine whether the dynamic credential is valid based on the challenge credential. For example, if credential validation module 340 determines that a dynamic credential, which belongs to a challenge-dynamic credential pair, corresponds with a challenge credential in the challenge-dynamic credential pair, then credential validation module 340 may determine that the dynamic credential is valid; otherwise, credential validation module 340 may determine that the dynamic credential is not valid.

Credential validation module 340 may authorize requests based on configuration 232. For purposes of illustrating a clear example, assume that configuration 232 includes data indicating that a particular web page is public. In response to a request for the particular web page, which does not include a dynamic credential, credential validation module 340 may authorize the request based on configuration 232.

3.2.6 Reverse Transformer

Reverse transformer 342 may translate requests intercepted by protocol server module 338, which are based on instructions generated by forward transformer 336, into requests that would have been generated by browser 295 had browser 295 received the original instructions sent from web infrastructure 205. For example, if a request from browser 295 includes a dynamic credential generated by credential validation module 340, then reverse transformer 342 may generate a new request that does not include the dynamic credential. Reverse transformer 342 may send the new request web infrastructure 205 through protocol client module 332 on behalf of browser 295.

3.2.7 Configurations

Configuration 242 may be a database, a configuration file, and/or any other system that stores configurations: settings, preferences, and/or protocols. Configuration 242 may store more than one configuration for one or more web servers in web infrastructure 205. For example, configuration 232 may include data that indicates requests to a particular server computer in web infrastructure 205 need not be validated. Additionally or alternatively, configuration 232 may include data that indicates requests for a particular web page need not be validated. Additionally or alternatively, configuration 232 may include data that indicates requests to submit data to a particular web site need not be validated. Also for example, configuration 232 may include data that indicates whether particular web pages should be processed by processing engine 334 and/or modified by forward transformer 336.

Configuration 232 may be modified by a user and/or administrator through one or more computers, such intermediary computer 230, a computer in web infrastructure 205, and/or any other computer. The one or more computers may present the user with an interface that presents the user with a site map. The site map may comprise a graph, wherein the nodes correspond to pages and the edges between the nodes correspond to links.

The user may update configuration 232, through the interface, by selecting which links and/or pages to be “public” (do not require a valid credential) and which links and/or pages are “private” (require a valid credential). For example, the interface may receive input from a user indicating that a page is public. Configuration 232 may be updated accordingly. When a request is received for the particular page, even if the request does not have a valid credential, intermediary computer 230 may pass the request to web infrastructure 205. Also for example, the interface may receive input from a user indicating that a link, with a particular link identifier, is public. When intermediary computer 230 receives a request that includes a particular link identifier, then intermediary computer 230 may pass the request to web infrastructure 205 even if the request does not have a valid credential.

3.2.8 Storage

Storage 240 may be a database, a configuration file, and/or any other system and/or data structure that stores data. In FIG. 2, storage 240 is illustrated as if a separate computer from intermediary computer 230. Additionally or alternatively, storage 240 may be a data structure stored in memory on the one or more computers comprising intermediary computer 230. Additionally or alternatively, storage 240 may, at least in part, be a data structure stored in shared memory between one or more intermediary computers. Additionally or alternatively, intermediary computer 230 may, at least in part, be stored in volatile and/or non-volatile memory.

3.3 Browser

Browser 295 may be a browser as described herein and executed on a client computer, such as client computer 299. Additionally or alternatively, browser 295 may be a bot comprising one or more of the components traditionally found in a browser.

4.0 Process Overview

In an embodiment, a data processing method may be configured to intercept instructions from a server computer that are directed toward a browser, modify the intercepted instructions, include one or more credential-morphing instructions, render a second set of instructions comprising the modified set of instructions and one or more credential-morphing instructions. In an embodiment, a data processing method may be configured to receive requests from a browser for a new credential from a client application, validate the request using a previous credential, generate the new credential, and send the new credential to the browser. In an embodiment, a data processing method may be configured to receive requests from a client computer for data on a server computer, validate the request based on a dynamic credential. In an embodiment, if the request is valid, then the processing method may be configured to modify the request, send the modified request to a server computer, receive data from the server computer in response to the modified request, and/or send a response to a client computer. Various embodiments may use standard web protocols, such as HTTP, and/or standard web-based instructions, such as HTML, CSS, and/or JavaScript. Additionally or alternatively, other standard and/or proprietary protocols may be used. Additionally or alternatively, other standard and/or proprietary instructions may be used.

4.1 Intercepting Instructions from a Content Server Computer

FIG. 4 illustrates a process for validating requests from browsers, and filtering out requests from bots, using one or more dynamic credentials in an example embodiment. In step 410, an intermediary computer intercepts, from a first computer, a first set of instructions that define one or more original operations, which are configured to cause one or more requests to be sent if executed by a client computer. For example, protocol client module 332 may receive instructions from web infrastructure 205. The instructions may comprise HTML, CSS, and/or JavaScript may define a web page. A web page may include data, such as objects, links, fields, forms, Uniform Resource Locators (“URLs”), that a browser may use to generate a request for additional data, such as another web page. A web page may be a sub-page of another page and/or include one or more other web pages. A browser may generate a request based on the data in the web page.

4.2 Modifying Instructions which Cause a Browser to Submit a Credential with One or More Requests

In step 420, the intermediary computer modifies the first set of instructions to produce a modified set of instructions, which if executed are configured to cause a credential to be included in the one or more requests sent by the client computer. For purposes of illustrating a clear example, assume that the instructions received in the previous step comprise HTML, CSS, and JavaScript instructions that define a link, which a browser or bot may use to generate a request for additional data and/or instructions. Processing engine 334 may parse the instructions. Forward transformer 336 may identify the link processed by processing engine 334. Forward transformer 336 may modify the instructions that define the link, such that if the link is selected by a user using a browser, then the browser executes a JavaScript callback that causes the browser to modify the URL, one or more parameters in the URL, and/or data submitted in a request based on the URL, to include a dynamic credential. Accordingly, when the browser generates the request based, at least in part on the URL, the request includes a dynamic credential. The foregoing is an example of a technique for modifying instructions to cause a browser to include a credential in a URL. Other embodiments may use one or more other techniques.

For purposes of illustrating another clear example, assume that the instructions received in the previous step define a form that is associated with a submit method. The submit method may be configured to collect data from one or more of the fields in the form and send the collected data in a request, such as an HTTP POST request, to a server computer. After processing engine 334 parses the instructions, forward transformer 336 may add a new field in the form that includes a dynamic credential. Accordingly, when the submit method is executed, the browser may generate a request that includes the credential stored in the added field with other data from other fields in the form. Additionally or alternatively, forward transformer may generate a wrapper for the previously defined submit method. The wrapper may be configured to call the previously defined submit method and tack on a credential in the payload of the request.

Additionally or alternatively, intermediary computer 230 may determine whether to parse and/or modify instructions based on configuration 232. For example, if protocol client module 332 receives a set of original instructions in response to a request for a particular web page, and configuration 232 includes data that indicates the particular web page is a public page and/or should not be modified, then processing engine 334 and/or forward transformer 336 may send the original instructions to the intended client computer without processing or modifying the instructions. Also for example, if processing engine 334 and/or forward transformer 336 determine that a set of instructions define a particular link to a particular target page and/or URL, and if configuration 232 includes data that indicates the particular link and/or the particular target page and/or URL are protected, then forward transformer 336 may modify the instructions that define the particular link. Similarly, if processing engine 334 and/or forward transformer 336 determine that a set of instructions define a particular link to a particular target page and/or URL, and if configuration 232 includes data that indicates the particular link and/or the particular target page and/or URL are public, then forward transformer 336 may modify the instructions that define the particular link.

In the above examples, the modified instructions may be executed by a browser using one or more particular parsers and/or execution environments, such as JavaScript parser 114, extension execution environment 116, and/or JavaScript execution environment 120. Thus, a bot without the particular parser(s) and/or execution environment(s) needed to parse and execute the modified instructions may not generate a request that includes a dynamic credential. Accordingly, a request for instructions and/or data from a bot may be dismissed, ignored, and/or other responded to in a negative manner.

The modified instructions need not include a valid credential. The modified instructions may merely cause a credential to be included in one or more requests sent by the client computer. How a valid dynamic credential is requested, received, and/or generated is discussed in detail herein.

4.2.1 Causing a Browser to Submit a Credential with One or More Requests Using a Browser Cookie

In one or more of the examples above, instructions that define an object, such as a link, field, button, and/or form, are modified to cause a browser to include a credential in a subsequent request. In another embodiment, an intermediary computer may include one or more instructions that cause a browser to send one or more credentials in a subsequent request without modifying the instructions that define an object in a web page that the subsequent request is based on. For example, an intermediary computer may include one or more instructions that store a credential as a browser cookie. A browser cookie may include data, such as one or more credentials or credential parameters. A browser cookie may include one or more cookie parameters, such as an expiration date and time, a domain, and/or path. If the browser makes a request and the one or more cookie parameters, if any, are satisfied, then the browser may include the data in the browser cookie, such as a credential, in the request. A browser cookie that includes one or more credentials, and/or one or more credential parameters, may be referred to herein as a credential cookie. A credential cookie may include a dynamic credential, a challenge credential, and/or a challenge-dynamic credential pair.

Instructions, which when executed by a browser may store a credential and/or credential parameters as one or more browser cookies, may be referred to herein as credential-cookie instructions. In various embodiments, credential-cookie instructions may comprise HTML and/or JavaScript instructions. Credential-cookie instructions may comprise, and/or be included in, dynamic-credential instructions, challenge-credential instructions, and/or credential-morphing instructions. Credential-cookie instructions may store one or more credentials, and/or one or more credential parameters, as one or more credential cookies.

Credential-cookie instructions for a credential may be encoded as structured data, such as XML and/or HTML. The structured data may be included a particular section in a document, such as a header section in an HTML document. A browser and/or a bot may parse the credential-cookie instructions comprising structured data and generate a credential cookie as discussed herein, without one or more instructions in a programming language that are configured to be executed in an execution environment. For example, forward transformer 336 may generate credential-cookie instructions that comprises a protocol header and/or structured data object that define a challenge credential as a credential cookie without including one or more JavaScript instructions configured to generate, process, and/or update the challenge credential. In an embodiment, the credential-cookie instructions may be a single line of structured data.

Additionally or alternatively, credential-cookie instructions may comprise executable instructions configured to be executed in an execution environment, which causes the execution environment in a browser to generate and/or update a credential as discussed herein. For example, forward transformer 336 may generate credential-cookie instructions that include dynamic-credential instructions that define, generate, and/or update a dynamic credential stored in a credential cookie. Accordingly, in an embodiment, a challenge credential may be generated by a browser and/or bot without executing one or more JavaScript instructions configured to generate, process, and/or update the challenge credential; however, a browser may execute one or more JavaScript instructions configured to generate, process, and/or update a dynamic credential for the same web page. If a bot does not include a JavaScript executing engine, then the bot may generate the challenge credential, but may not generate, process, and/or update a dynamic credential for the same web page.

Forward transformer 336 may include credential-cookie instructions into one or more files and/or instructions that define a web page, without modifying the instructions that define an object in the web page. Additionally or alternatively, forward transformer 336 may include credential-cookie instructions in a separate file, and include a reference to the separate file in the web page, without modifying the instructions that define an object in the web page. In an embodiment, forward transformer 336 may generate credential instructions that are configured to cause browser 295 to generate a credential after a web page has finished loading. For example, dynamic-credential instructions may be configured to be executed, at least partially, in response to browser 295 calling an “onload” page event and/or callback.

For purposes of illustrating a clear example of an intermediary computer preforming step 420 using a credential cookie, assume that the instructions received in step 410 comprise HTML, CSS, and JavaScript instructions that define a web page with a link, which a browser or bot may use to generate a request for additional data. Forward transformer 336 may include credential-cookie instructions that define a cookie credential in the HTML, CSS, and JavaScript instructions received in in the previous. Accordingly, if the link is selected by a user using a browser, then the browser may generate a request based on the link, and the request may include one or more credentials, and/or credential parameters, stored in the cookie credential.

4.3 Rendering a Second Set of Instructions Comprising Credential-Morphing Instructions

In step 430, the intermediary computer renders a second set of instructions comprising the modified set of instructions and one or more credential-morphing instructions. The one or more credential-morphing instructions may define one or more operations causing a browser with a particular parser and/or execution environment to request, receive, generate, and/or update a valid credential that changes over time. For example, forward transformer 336 may render a second set of instructions that include the modified instructions and credential morphing-instructions comprising one or more JavaScript instructions, which if parsed and/or executed are configured to cause a browser to request, receive, generate, and/or update a valid credential that changes over time. Additionally or alternatively, forward transformer 336 may include the credential-morphing instructions by including a reference to a file with credential-morphing instructions, such as an additional JavaScript file, in the rendered instructions.

If a bot does not have the particular parser and/or execution environment necessary to execute the credential-morphing instructions, then the bot may not have a valid dynamic credential to submit with a subsequent request. Accordingly, subsequent requests from bots may be dismissed, ignored, and/or otherwise negatively dealt with as discussed herein. However, requests from browsers may be processed as if uninterrupted by an intermediary.

4.4 Sending the Modified and Credential-Morphing Instructions to the Client Computer

In step 440, the intermediary computer sends the second set of instructions, which comprise the modified instructions and the credential morphing-instructions to the client computer. For example, forward transformer 336 may send the modified instructions in step 420 and the credential-morphing instructions in step 430 to browser 295.

4.5 Updating the Credential Over Time

In step 450, the client computer parses and/or executes the credential-morphing instructions and updates the credential over time. The credential-morphing instructions may cause the client computer, and/or browser executing on the client computer, to perform one or more methods to update a credential over time. In an embodiment, the credential may be stored in storage on a client computer, intermediary computer, and/or storage. The storage may, but need not be, non-volatile storage. When a new credential is received and/or generated, the old credential is deleted. Each newly received and/or generated credential may replace a previous credential at the particular address in memory that the previous credential was stored.

FIG. 5 illustrates a process for updating a credential over time in an example embodiment. In step 510, the intermediary computer receives a request for a new credential. For purposes of illustrating a clear example, assume that browser 295 receives the second set of instructions sent in step 440, and that the credential-morphing instructions, if executed, are configured to cause browser 295 to request a new credential from intermediary computer 230. Accordingly, browser 295 may parse and/or execute the credential-morphing instructions using JavaScript parser 114 and JavaScript execution environment 120 to send a request for a new credential to intermediary computer 230. If browser 295 has already received and/or generated a credential, then browser 295 may send one or more of the previously received and/or generated credential in the request. Protocol server module 338 may receive the request and forward the request to credential validation module 340.

4.6 Validating a Credential

In step 520, the intermediary computer determines whether the credential is valid. For example, credential validation module 340 may determine that the old credential is valid if it is stored in storage 240 and/or other storage device. Additionally or alternatively, credential validation module 340 may determine that a credential is valid based on one or more implied and/or express parameters. If credential validation module 340 determines that each of the parameters is satisfied, then control may pass to step 530. Otherwise, control may pass to step 480.

Credential validation module 340 may delete a credential and/or one or more parameters associated with the credential after credential validation module 340 validates the credential. Thus, credential validation module 340 need not validate the same credential more than once.

Bots may request additional web pages quickly compared to a user viewing a page and selecting a link. To thwart and slow down one or more requests from bots, a credential may have a parameter that indicates the credential is invalid for a first amount of time before it becomes valid for a second period of time. Thus, if a bot is able to determine a valid credential and quickly sends a request with the credential to the intermediary computer, the intermediary computer may determine that the credential is invalid and pass to step 480.

A credential may be associated and/or embedded with one or more implied and/or express parameters. For example, a credential may be, and/or be associated with, a timestamp, a time range, an IP address, a subnet, a browser identifier, a username, a password, a keyword, a randomly generated value, and/or any other identifier and/or key that may be used to determine whether a credential is valid.

4.6.1 Implied Parameters

An implied parameter may be a parameter that is inherent to the credential. For example, a credential may be based on time, and credential validation module 340 may determine the time from the credential. Credential validation module 340 may be configured to determine that a credential is valid if the determined time is within a particular amount of time from the current time. Similarly, credential validation module 340 may be configured to determine that a credential is invalid if the determined timestamp identifies a time that is outside a particular amount of time from the current time.

4.6.2 Express Parameters

An express parameter may be a parameter that is associated with, and/or embedded in, a credential. For example, a credential may be associated with a parameter stored in storage 240, which indicates the time at which the credential is no longer valid. Credential validation module 340 may query for the parameter stored in storage 240 based on the credential. If the current time is less than the time retrieved from storage 240, then credential validation module 340 may determine that the old credential is valid. Otherwise, credential validation module 340 may determine that the credential is invalid.

Additionally or alternatively, a credential may include one or more encrypted parameters. Instead of storing one or more parameters in storage 240, credential validation module 340 may generate a credential that comprises one or more encrypted parameters. Credential validation module 340 may validate the credential by decrypting the one or more encrypted parameters and determining whether each of the decrypted parameters is satisfied. If so, then credential validation module 340 may determine the credential is valid. Otherwise, credential validation module 340 may determine the credential is invalid.

4.7 Generating a New Credential

In step 530, the intermediary computer generates a new credential. For example, credential validation module 340 may generate a new credential with one or more implied and/or express parameters. The one or more parameters may include any of the parameters discussed above, and/or any other value, identifier, and/or key that may be used to determine whether the new credential is valid. Credential validation module 340 may store the new credential and/or the one or more parameters in storage 240. Additionally or alternatively, credential validation module 340 may embed one or more parameters in the new credential.

4.7.1 Generating a First Credential

Intermediary computer 230 may not have an old credential to validate. For example, when a browser, such as browser 295, requests a page and/or credential from intermediary computer 230 for the first time, browser 295 may not have an old credential for intermediary computer 230 to validate. If intermediary computer 230 receives a request for a new credential without an old credential to validate, then intermediary computer 230 may generate a credential as discussed in detail herein. Additionally, the credential may be an “initialization credential”, which may be used by the browser, and/or the credential-morphing instructions, to request a new valid credential

If intermediary computer 230 receives a request from browser 295 for a new credential with an initialization credential and determines the initialization credential is valid, then intermediary computer 230 may respond with a valid new credential as discussed herein. However, if intermediary computer 230 receives a request from browser 295 for a web page from web infrastructure 205 with an initialization credential, then control may pass to step 480.

In an embodiment, forward transformer 336 may include a credential with the credential morphing-instructions. The credential may be an initialization credential. However, in an embodiment, forward transformer 336 need not include a credential with the credential morphing-instructions.

4.8 Sending a New Credential

In step 540, the intermediary computer may send the new credential to the client computer. For example, credential validation module 340 may send the credential to browser 295 through protocol server module 338.

In an embodiment, credential validation module 340 may send the new credential to forward transformer 336. Forward transformer 336 may generate one or more new credential-morphing instructions which when executed operate on the credential and/or request a new credential. For example, if executed, the one or more instructions may be configured to replace the previous credential in memory on the client computer. Additionally or alternatively, if executed, the one or more instructions may be configured to indicate when the client computer and/or browser should send a new request for a new credential. Additionally or alternatively, if executed, the one or more instructions may be configured to generate a new credential.

4.8.1 Sending a Seed Value from which the New Credential may be Generated

Forward transformer may generate a seed value from a new credential generated by credential validation module, which may be used to generate the new credential by the client computer. FIG. 6 illustrates a process for generating a seed value and sending the seed value to the client computer to generate one or more new credentials in an example embodiment. In step 610, the intermediary computer 230 generates a seed. For purposes of illustrating a clear example, assume forward transformer 336 receives a new credential from credential validation module 340 to be sent to a browser. Forward transformer 336 may generate a seed value based on the new credential. In an embodiment, a seed value may be a challenge credential.

In step 620, the intermediary computer sends the seed value to the client computer. For example, forward transformer 336 sends the seed value to browser 295.

In step 630, the client computer generates a new credential based on the seed or a previous credential. For example, browser 295 may execute one or more credential-morphing instructions, which may be configured to generate a valid credential based on a seed received from intermediary computer 230. In an embodiment, over time, browser 295 may execute the credential-morphing instructions again to generate a new valid credential based on one or more previously generated valid credentials.

4.9 Updating a Credential Over Time

The intermediary computer may repeat steps 450 according to the credential-morphing instructions. For example, the credential morphing-instructions may define a time period, after which a browser should request, receive, generate, and/or update a new credential as discussed in detail herein.

Forward transformer 336 may render and send one or more new credential morphing-instructions with each credential and/or a seed, which if executed, may be configured to cause the client computer and/or browser to request and/or generate a new credential. The one or more new credential-morphing instructions may be different than one or more previously sent credential-morphing instructions.

4.10 Validating a Request for Data

Returning now to FIG. 4, in step 460, the intermediary intercepts a request for data. For example, protocol server module 338 may receive a request from browser 295 for data and/or instructions, such as a web page, from web infrastructure 205.

In step 470, the intermediary computer determines whether the request is valid by determining if the credential included in the request, if any, is valid. For example, protocol server module 338 may forward the request to credential validation module 340. Credential validation module 340 may determine whether the credential is valid based on one or more of the methods discussed herein. If credential validation module 340 determines the credential is valid, then control passes to step 490. Otherwise, control passes to step 480. If credential validation module 340 determines that the request does not include a credential, then control may pass to step 480. If credential validation module 340 determines that the request for data includes an initializing credential, then control may pass to step 480.

If configuration 232 includes data indicating that the data requested is public, such as a home page of a web site, then credential validation module 340 may determine that the request is valid, even though the request did not include a credential. In response, control may pass to step 490. If, however, configuration 232 includes data indicating that the data requested is public, but the request includes an invalid credential, then control may pass to step 480.

4.11 Performing a Negative Responsive Action

In step 480, the intermediary computer performs a negative responsive action. For example, credential validation module 340 may terminate the request. Additionally or alternatively, credential validation module 340 may treat the request as a request for an initializing credential, and in response, generate and send the initializing credential and/or seed value to browser 295 via forward transformer 336, as discussed herein in detail. Additionally or alternatively, the intermediary computer 230 may respond with a message defined by a user and/or administrator through a client computer and/or the intermediary computer. Additionally or alternatively, intermediary computer 230 may respond with one or more standard and/or proprietary error codes and/or messages. For example, intermediary computer may return HTTP error code 400 and a message “Bad Request” to browser 295 and/or client computer 299. Intermediary computer may send a configurable response that indicates the request was invalid; the configurable response may be selected by an administrator and/or stored in configuration 232.

4.12 Forwarding the Request to a Server Computer

In step 490, the intermediary computer forwards the request for data to the server computer. For example, credential validation module 340 may pass the request to reverse transformer 342. Reverse transformer 342 may strip out data relating to the credential and produce a new request which would have been generated by browser 295 had the original instructions been received by browser 295. Reverse transformer 342 may send the new request to web infrastructure 205 through protocol client module 332.

If web infrastructure 205 responds to a forwarded request with data and/or instructions, then intermediary computer 230 may repeat one or more of the steps discussed herein. For example, intermediary computer 230 may perform step 410 in response to receiving the new data and/or instructions from web infrastructure 205.

5.0 Process Overview Using Challenge-Dynamic Credential Pairs

In an embodiment, an intermediary computer may be configured to inject one or more challenge-dynamic credential pairs into one or more instructions that define a web page, a portion of a web page, and/or data to be included in a web page, and send the one or more instructions with the one or more challenge-dynamic credential pairs to a client computer. In response to a request from the client computer, the intermediary may be configured to receive the request, determine whether the request includes a valid dynamic credential based on a challenge credential. If the intermediary determines that the dynamic credential is valid, then the intermediary computer may forward the request to a server computer; otherwise, the intermediary may perform one or more negative responsive actions.

FIG. 7 illustrates a process for validating requests from browsers, and filtering out requests from bots, using one or more dynamic credentials and one or more challenge credentials, in an example embodiment. In step 710, an intermediary computer intercepts, from an application server computer, a first set of instructions that define one or more original operations, which are configured to cause one or more requests to be sent if executed by a client computer. For example, protocol client module 332 may receive instructions from web infrastructure 205. The instructions may comprise HTML, CSS, and/or JavaScript that define a web page. A server computer included in web infrastructure, and/or a server computer that hosts one or more instructions that comprise a web page, may be referred to herein as an application server computer.

5.1 Generating a Challenge-Dynamic Credential Pair

In step 720, the intermediary computer generates a challenge credential. For purposes of illustrating a clear example, assume configuration 232 includes data that indicates a challenge credential should be a random value selected from a particular distribution, such as a Gaussian distribution with a particular mean, variance, maximum and minimum. Forward transformer 336 may request a challenge credential from credential validation module 340. Credential validation module 340 may select a value according to the Gaussian distribution and send the value to forward transformer 336. Forward transformer 336 may render credential-cookie instructions that include the challenge credential.

In step 730, the intermediary computer renders one or more dynamic-credential instructions that cause the client computer to generate a dynamic credential that corresponds to the challenge credential (a challenge-dynamic credential pair) and to include the dynamic credential in the one or more requests from the client computer. For example, forward transformer 336 may request a dynamic credential from credential validation module 340 that corresponds to the challenge credential generated in the previous step. After receiving a dynamic credential that corresponds to the challenge credential from credential validation module 340, forward transformer 336 may render one or more dynamic-credential instructions. The one or more dynamic-credential instructions may comprise, and/or be included in, one or more credential-cookie instructions.

There are many ways that credential validation module 340 may generate a dynamic credential that corresponds to, and/or is based on, the challenge credential. For purposes of illustrating a clear example, assume the challenge credential is an integer, and configuration 232 includes data that indicates a valid dynamic credential should be the result of an operation based on, and/or a transformation of, the challenge credential, such as the product of the challenge credential, a prime number, and/or the current number of seconds since an epoch. Credential validation module 340 may generate a challenge-credential pair, wherein the dynamic credential that is a multiple of the challenge credential generated in the previous step, the prime number, and/or the current number of seconds since the epoch.

For purposes of illustrating another clear example, assume configuration 232 includes data that indicates a dynamic credential should be a random value selected from a particular distribution, such as a uniform distribution ranging from a minimum value to a maximum value. Credential validation module 340 may generate a dynamic credential with a random value selected according to the uniform distribution. Credential validation module 340 and/or forward transformer 336 may store a mapping in storage 240 that associates the dynamic credential and the challenge credential.

In step 740, the intermediary computer modifies the first set of instructions to produce a second set of instructions that include the challenge credential and the one or more dynamic-credential instructions, and which when executed by the client computer, cause the challenge credential to be included in the one or more requests sent from the client computer when executed by the client computer. For example, forward transformer 336 may include the credential-cookie instructions for the challenge cookie generated in step 730, and the credential-cookie instructions for the dynamic cookie generated in step 740, in the one or more instructions received in step 710 to produce a modified set of instructions that define a web page with a valid challenge-dynamic credential pair.

In step 750, the intermediary computer sends the second set of instructions to the client computer. For example, forward transformer 336 may send, to browser 295 through protocol server module 338, the one or more instructions with instructions comprising protocol headers, structured data, and/or executable instructions, which when executed by a browser generate a valid challenge-dynamic credential pair stored in one or more credential cookies.

5.2 Updating a Challenge-Dynamic Credential Pair

A dynamic credential in a challenge-dynamic credential pair may be updated over time according to one or more of the methods discussed herein. For example, browser 295 may execute one or more instructions that cause browser 295 to send a request for a new dynamic credential to intermediary computer 230. The request may include the dynamic credential and the challenge credential in the challenge-dynamic credential pair. Credential validation module 340 may validate the dynamic credential based on the challenge credential, generate a new dynamic credential, and send the new dynamic credential and/or or the challenge credential to browser 295. After a dynamic credential in a particular challenge-dynamic credential pair is updated using one or more of the systems and/or methods discussed herein, credential validation module 340 and/or forward transformer 336 may update the mapping in storage 240 with data indicating that the new, updated dynamic credential, and/or not the previous dynamic credential, is associated with the challenge credential in the particular challenge-dynamic credential pair.

In an embodiment, a challenge credential may also be a dynamic credential. The challenge credential may be generated and/or updated using the same one or more methods discussed herein with a dynamic credential. After a challenge credential in a particular challenge-dynamic credential pair is updated using one or more of the systems and/or methods discussed herein, credential validation module 340 and/or forward transformer 336 may update the mapping in storage 240 with data indicating that the new, updated challenge credential, and/or not the previous challenge credential, is associated with the dynamic credential in the particular challenge-dynamic credential pair.

5.3 Determining Whether a Dynamic Credential in a Challenge-Dynamic Credential Pair is Valid

Referring again to FIG. 7, in step 760, the intermediary computer receives a request for data. For example, browser 295 may receive input indicating that a user selected a particular link in the web page sent to browser 295 in step 750. In response, browser 295 may generate a request based on the particular link and include a challenge credential and/or a dynamic credential. Credential validation module 340 may receive the request through protocol server module 338.

In step 770, the intermediary computer may determine whether the dynamic credential, if included in the request, is valid. If so, then control may pass to step 790; otherwise, control may pass to stop 780. For example, if the request includes a challenge credential, but not a dynamic credential, then credential validation module 340 may determine browser 295 is a bot and/or control may pass to step 780. Similarly, if the request includes a dynamic credential, but not a challenge credential, then credential validation module 340 may determine browser 295 is a bot and/or control may pass to step 780.

If the request includes a challenge credential and a dynamic credential, then credential validation module 340 may determine whether the dynamic credential corresponds with the challenge credential to form a valid challenge-dynamic credential pair. For example, credential validation module 340 may determine whether a mapping in storage 240 associates the challenge credential to the dynamic credential in the request. If so, then credential validation module 340 may determine that the dynamic credential corresponds with the challenge credential, browser 295 is a legitimate browser, browser 295 is not a bot, and/or control may pass to step 790; otherwise, credential validation module 340 may determine that the dynamic credential does not correspond with the challenge credential, browser 295 is not a legitimate browser, browser 295 is a bot, and/or control may pass to step 780.

Credential validation module 340 may determine whether a dynamic credential corresponds with a challenge credential based on configuration 232. For example, if configuration 232 indicates that a dynamic credential should be a transformation of, and/or based on, the challenge credential to be a valid challenge-dynamic credential pair, then credential validation module 340 may perform one or more transformations on the dynamic credential to produce a transformed credential, and determine if the transformed credential matches the challenge credential. If so, then credential validation module 340 may determine that the dynamic credential corresponds with the challenge credential, browser 295 is a legitimate browser, browser 295 is not a bot, and/or control may pass to step 790; otherwise, credential validation module 340 may determine that the dynamic credential does not correspond with the challenge credential, browser 295 is not a legitimate browser, browser 295 is a bot, and/or control may pass to step 780.

In step 780, the intermediary computer may perform a negative responsive action, such as the one or more responsive actions discussed herein. In step 790, the intermediary computer may forward the request to a server computer as discussed herein.

6.0 Implementation Mechanisms—Hardware Overview

According to one embodiment, the techniques described herein are implemented by one or more special-purpose computing devices. The special-purpose computing devices may be hard-wired to perform the techniques, or may include digital electronic devices such as one or more application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs) that are persistently programmed to perform the techniques, or may include one or more general purpose hardware processors programmed to perform the techniques pursuant to program instructions in firmware, memory, other storage, or a combination. Such special-purpose computing devices may also combine custom hard-wired logic, ASICs, or FPGAs with custom programming to accomplish the techniques. The special-purpose computing devices may be desktop computer systems, portable computer systems, handheld devices, networking devices or any other device that incorporates hard-wired and/or program logic to implement the techniques.

For example, FIG. 8 is a block diagram that illustrates a computer system 800 upon which an embodiment of the invention may be implemented. Computer system 800 includes a bus 802 or other communication mechanism for communicating information, and a hardware processor 804 coupled with bus 802 for processing information. Hardware processor 804 may be, for example, a general purpose microprocessor.

Computer system 800 also includes a main memory 806, such as a random access memory (RAM) or other dynamic storage device, coupled to bus 802 for storing information and instructions to be executed by processor 804. Main memory 806 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 804. Such instructions, when stored in non-transitory storage media accessible to processor 804, render computer system 800 into a special-purpose machine that is customized to perform the operations specified in the instructions.

Computer system 800 further includes a read only memory (ROM) 808 or other challenge storage device coupled to bus 802 for storing challenge information and instructions for processor 804. A storage device 810, such as a magnetic disk or optical disk, is provided and coupled to bus 802 for storing information and instructions.

Computer system 800 may be coupled via bus 802 to a display 812, such as a cathode ray tube (CRT), for displaying information to a computer user. An input device 814, including alphanumeric and other keys, is coupled to bus 802 for communicating information and command selections to processor 804. Another type of user input device is cursor control 816, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor 804 and for controlling cursor movement on display 812. This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane.

Computer system 800 may implement the techniques described herein using customized hard-wired logic, one or more ASICs or FPGAs, firmware and/or program logic which in combination with the computer system causes or programs computer system 800 to be a special-purpose machine. According to one embodiment, the techniques herein are performed by computer system 800 in response to processor 804 executing one or more sequences of one or more instructions contained in main memory 806. Such instructions may be read into main memory 806 from another storage medium, such as storage device 810. Execution of the sequences of instructions contained in main memory 806 causes processor 804 to perform the process steps described herein. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions.

The term “storage media” as used herein refers to any non-transitory media that store data and/or instructions that cause a machine to operation in a specific fashion. Such storage media may comprise non-volatile media and/or volatile media. Non-volatile media includes, for example, optical or magnetic disks, such as storage device 810. Volatile media includes dynamic memory, such as main memory 806. Common forms of storage media include, for example, a floppy disk, a flexible disk, hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, a CD-ROM, any other optical data storage medium, any physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, NVRAM, any other memory chip or cartridge.

Storage media is distinct from but may be used in conjunction with transmission media. Transmission media participates in transferring information between storage media. For example, transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise bus 802. Transmission media can also take the form of acoustic or light waves, such as those generated during radio-wave and infra-red data communications.

Various forms of media may be involved in carrying one or more sequences of one or more instructions to processor 804 for execution. For example, the instructions may initially be carried on a magnetic disk or solid state drive of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system 800 can receive the data on the telephone line and use an infra-red transmitter to convert the data to an infra-red signal. An infra-red detector can receive the data carried in the infra-red signal and appropriate circuitry can place the data on bus 802. Bus 802 carries the data to main memory 806, from which processor 804 retrieves and executes the instructions. The instructions received by main memory 806 may optionally be stored on storage device 810 either before or after execution by processor 804.

Computer system 800 also includes a communication interface 818 coupled to bus 802. Communication interface 818 provides a two-way data communication coupling to a network link 820 that is connected to a local network 822. For example, communication interface 818 may be an integrated services digital network (ISDN) card, cable modem, satellite modem, or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, communication interface 818 may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, communication interface 818 sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

Network link 820 typically provides data communication through one or more networks to other data devices. For example, network link 820 may provide a connection through local network 822 to a host computer 824 or to data equipment operated by an Internet Service Provider (ISP) 826. ISP 826 in turn provides data communication services through the world wide packet data communication network now commonly referred to as the “Internet” 828. Local network 822 and Internet 828 both use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on network link 820 and through communication interface 818, which carry the digital data to and from computer system 800, are example forms of transmission media.

Computer system 800 can send messages and receive data, including program code, through the network(s), network link 820 and communication interface 818. In the Internet example, a server 830 might transmit a requested code for an application program through Internet 828, ISP 826, local network 822 and communication interface 818.

The received code may be executed by processor 804 as it is received, and/or stored in storage device 810, or other non-volatile storage for later execution.

7.0 Other Aspects of Disclosure

Using the networked computer arrangements, intermediary computer, and/or processing methods described herein, security in client-server data processing may be significantly increased. Dynamic credential techniques discussed herein effectively reduce automated attacks. Consequently, one or more various attacks, such as a denial of service (“DOS”) attack, credential stuffing, fake account creation, ratings or results manipulation, man in the browser attacks, reserving rival goods or services, scanning for vulnerabilities, and/or exploitation of vulnerabilities, are frustrated because requests are accompanied by a credential that changes over time.

In the foregoing specification, embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the invention, and what is intended by the applicants to be the scope of the invention, is the literal and equivalent scope of the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction.

Aspects of the subject matter described herein are set out in the following numbered clauses:

1. An intermediary computer system comprising: a memory; a processor coupled to the memory; a protocol client module that is coupled to the processor and the memory and configured to intercept a first set of instructions that define one or more original operations, which are configured to cause one or more requests to be sent to the server computer when executed by the client computer; a forward transformer module that is coupled to the processor and the memory and configured to: generate, at the intermediary computer system, a first challenge credential to be sent to the client computer; render one or more first dynamic-credential instructions, which when executed by the client computer, cause the client computer to generate a first dynamic credential that corresponds to the first challenge credential and to include the first dynamic credential in the one or more requests from the client computer; modify the first set of instructions to produce a second set of instructions, wherein the second set of instructions include the first challenge credential and the one or more first dynamic-credential instructions, and which when executed by the client computer, cause the first challenge credential to be included in the one or more requests sent from the client computer; send the second set of instructions to a second computer.

2. The intermediary computer system of clause 1 further comprising: a protocol server module coupled to the processor and the memory and configured to receive a request for data; a credential validation module coupled to the processor and the memory and configured to perform a negative responsive action in response to determining the request does not include a dynamic credential.

3. The intermediary computer system of any clause 1-2 further comprising: a protocol server module coupled to the processor and the memory and configured to receive a request for data that includes the first challenge credential and a dynamic credential; a credential validation module coupled to the processor and the memory and configured to perform a negative responsive action in response to determining the challenge credential and the dynamic credential included in the request does not correspond to the first challenge credential.

4. The intermediary computer system of any clause 1-3, wherein the credential validation module is further configured to send a configurable response that indicates the request was invalid as at least part of performing the negative responsive action.

5. The intermediary computer system of any clause 1-4 further comprising: a protocol server module coupled to the processor and the memory and configured to receive a request for data that includes a challenge credential and a dynamic credential; a credential validation module coupled to the processor and the memory and configured to determine that the challenge credential is the first challenge credential and determine that the dynamic credential is the first dynamic credential and corresponds to the first challenge credential; a reverse transformer coupled to the processor and the memory and configured to forward at least a portion of the request to the server computer in response to the credential validation module determining that the first dynamic credential corresponds to the first challenge credential.

6. The intermediary computer system of any clause 1-5, wherein the credential validation module is configured to determine that the first dynamic credential corresponds to the first challenge credential by determining a value stored in the intermediary computer system and associated with the first challenge credential matches the first dynamic credential.

7. The intermediary computer system of any clause 1-6, wherein the credential validation module is configured to determine that the first dynamic credential corresponds to the first challenge credential by performing one or more transformations to the dynamic credential to produce a transformed credential and determining that the transformed credential matches the first challenge credential.

8. The intermediary computer system of any clause 1-7, wherein: the protocol client module is further configured to intercept a third set of instructions, which when executed by the client computer cause one or more second requests to be sent to the server computer; the forward transformer module is further configured to: generate, at the computer, a second challenge credential to be sent to the client computer, wherein the second challenge credential is different than the first challenge credential; render one or more second dynamic-credential instructions, which when executed by the client computer, cause the client computer to generate a second dynamic credential that corresponds to the first challenge credential and to include the second dynamic credential in the one or more second requests from the client computer, wherein the second dynamic credential is different than the first dynamic credential; modify the third set of instructions to produce a fourth set of instructions, wherein the fourth set of instructions include the second challenge credential and the one or more second dynamic-credential instructions, and which when executed by the client computer, cause the second challenge credential to be included in the one or more requests sent from the client computer when executed by the client computer; and send the fourth set of instructions to the second computer.

9. The intermediary computer system of any clause 1-8, wherein the first set of instructions comprises a web page and the second set of instructions includes a subset of instructions that cause the first challenge credential to be stored as a first cookie associated with the web page when the second set of instructions are executed by the client computer; wherein the subset of instructions are not the one or more first dynamic-credential instructions; wherein the one or more first dynamic-credential instructions cause the first dynamic credential to be stored as a second cookie associated with the same web page when the second set of instructions are executed by the client computer.

10. The intermediary computer system of any clause 1-9, wherein the subset of instructions is a single line of structured data within a header section defined in the web page, and the one or more first dynamic-credential instructions are configured to be executed after the web page is loaded by a browser being executed on the second computer.

11. The intermediary computer system of any clause 1-10, wherein the second set of instructions include the one or more first dynamic-credential instructions by reference.

12. The intermediary computer system of any clause 1-11 further comprising: a protocol server module coupled to the processor and the memory and configured to receive a request for data that includes a challenge credential and a dynamic credential; a credential validation module coupled to the processor and the memory and configured to: determine that the challenge credential is the first challenge credential and associated with a one or more first parameters; determine that the dynamic credential is the first dynamic credential and associated with one or more second parameters; determine that the dynamic credential corresponds to the first challenge credential, the one or more first parameters are satisfied and the one or more second parameters are satisfied; a reverse transformer coupled to the processor and the memory and configured to forward at least a portion of the request to the server computer in response to the credential validation module determining that the one or more first parameters are satisfied, the one or more second parameters are satisfied, and the first dynamic credential corresponds to the first challenge credential.

13. A non-transitory computer-readable data storage medium storing one or more sequences of instructions, which when executed cause one or more processors to perform any of the features recited in any clause 1-12

14. A computer program product including instructions, which when implemented on one or more processors, carries out any of the features recited in any clause 1-12.

15. A method, which when implemented on one or more processors, carries out any of the features recited in any clause 1-12.

16. A method comprising: receiving a one or more instructions that define a first challenge credential, one or more first dynamic-credential instructions, and a first object to be displayed to a user; storing the first challenge credential; executing the one or more first dynamic-credential instructions to produce a first dynamic credential that corresponds to the first challenge credential; causing displaying the object; receiving a first input from the user indicating that the user selected the first object, and in response, sending a first request to a server computer for a first set of data, wherein the first request is based on the object and includes the first challenge credential and the first dynamic credential; receiving, from the server computer, the first set of data and one or more second dynamic-credential instructions, and in response, executing the one or more second dynamic-credential instructions to produce a second dynamic credential that corresponds to the first challenge credential, wherein the one or more second dynamic-credential instructions are different than the one or more first dynamic-credential instructions and the second dynamic credential is different than the first dynamic credential; wherein the method is performed by one or more computing devices.

17. The method of clause 16 further comprising: receiving a second input from the user, and in response, sending a second request to the server computer for a second set of data, wherein the second request comprises the first challenge credential and the second dynamic credential; receiving, from the server computer and in response to the second request that included the first challenge credential and the second dynamic credential that corresponds to the first challenge credential, the second set of data.

18. The method of any clause 16-17 further comprising: receiving the second set of data comprising a second challenge credential that corresponds to the second dynamic credential; storing the second challenge credential and deleting the first challenge credential; receiving a third input from the user, and in response, sending a third request to the server computer for a third set of data, wherein the third request comprises the second challenge credential and the second dynamic credential; receiving, from the server computer and in response to the third request that included the first challenge credential and the second dynamic credential that corresponds to the first challenge credential, the third set of data.

19. The method of any clause 16-18 further comprising: after a particular time, receiving a second input from the user, and in response, sending a second request to the server computer for a second set of data, wherein the second request comprises the first challenge credential and the second dynamic credential; receiving, from the server computer and in response to the second request that included the first challenge credential and the second dynamic credential that no longer corresponds to the first challenge credential, an error indicating that the request is not valid because the second dynamic credential does not correspond with the first challenge credential.

20. The method of any clause 16-19, wherein storing the first challenge credential comprises storing the first challenge credential as a browser cookie that is configured to be included in any request for data from a particular domain.

21. The method of any clause 16-20, wherein executing the one or more first dynamic-credential instructions causing storing the first dynamic credential as a browser cookie that is configured to be included in any request for data from a particular domain.

22. The method of any clause 16-21, wherein executing the one or more first dynamic-credential instructions causing generating the first dynamic credential based on a value of the first challenge credential.

23. A non-transitory computer-readable data storage medium storing one or more sequences of instructions, which when executed cause one or more processors to perform any of the features recited in any clause 16-22.

24. A computer program product including instructions, which when implemented on one or more processors, carries out any of the features recited in any clause 16-22.

25. A method, which when implemented on one or more processors, carries out any of the features recited in any clause 16-22. 

What is claimed is:
 1. A server system programmed to validate requests from a client computer, the system comprising: one or more processors; one or more non-transitory computer-readable media storing instructions which, when executed by the one or more processors, cause: generating, at the server system, a first challenge credential to be sent to the client computer; rendering one or more first dynamic-credential instructions based on the first challenge credential, which when executed by the client computer, cause the client computer to generate a first dynamic credential that corresponds to the first challenge credential, to update the first dynamic credential one or more times, and to include the updated first dynamic credential in one or more first requests from the client computer; generating a first set of instructions including the first challenge credential and the one or more first dynamic-credential instructions, wherein the first set of instructions, when executed by the client computer, cause the first challenge credential to be included in the one or more first requests sent from the client computer; sending the first set of instructions to the client computer; receiving a request for data from the client computer; determining, based on the request, whether the client computer is a bot.
 2. The server system of claim 1 wherein determining whether the client computer is a bot is based on whether the request incudes a dynamic credential and a challenge credential.
 3. The server system of claim 2 wherein the request includes a challenge credential and a dynamic credential and wherein determining whether the client computer is a bot is based on determining whether the challenge credential is the first challenge credential.
 4. The server system of claim 2 wherein determining whether client is a bot is further based on determining whether the dynamic credential included in the request corresponds to the challenge credential.
 5. The server system of claim 4 wherein determining whether the dynamic credential corresponds to the challenge credential comprises determining a value stored in the server system and associated with the challenge credential matches the dynamic credential.
 6. The server system of claim 4 wherein determining whether the dynamic credential corresponds to the challenge credential comprises performing one or more transformations to the dynamic credential to produce a transformed credential and determining that the transformed credential matches the challenge credential.
 7. The server system of claim 1, the instructions including instructions which, when executed by the one or more processors, further cause: in response to determining that the client computer is a bot, performing one or more negative response actions.
 8. The server system of claim 7 wherein the negative response action comprises generating an error code.
 9. The server system of claim 7 wherein the negative response action comprises generating an error message.
 10. The server system of claim 7 wherein the negative response action comprises sending a negative response to the client computer.
 11. A method for validating requests from a client computer, the method comprising: generating, at a server system, a first challenge credential to be sent to the client computer; rendering one or more first dynamic-credential instructions based on the first challenge credential, which when executed by the client computer, cause the client computer to generate a first dynamic credential that corresponds to the first challenge credential, to update the first dynamic credential one or more times, and to include the updated first dynamic credential in one or more first requests from the client computer; generating a first set of instructions including the first challenge credential and the one or more first dynamic-credential instructions, wherein the first set of instructions, when executed by the client computer, cause the first challenge credential to be included in the one or more first requests sent from the client computer; send the first set of instructions to the client computer; receiving a request for data from the client computer; determining, based on the request, whether the client computer is a bot.
 12. The method of claim 11 wherein determining whether the client computer is a bot is based on whether the request incudes a dynamic credential and a challenge credential.
 13. The method of claim 12 wherein the request includes a challenge credential and a dynamic credential and wherein determining whether the client computer is a bot is based on determining whether the challenge credential is the first challenge credential.
 14. The method of claim 13 wherein determining whether client is a bot is further based on determining whether the dynamic credential included in the request corresponds to the challenge credential.
 15. The method of claim 14 wherein determining whether the dynamic credential corresponds to the challenge credential comprises determining a value stored in the server system and associated with the challenge credential matches the dynamic credential.
 16. The method of claim 14 wherein determining whether the dynamic credential corresponds to the challenge credential comprises performing one or more transformations to the dynamic credential to produce a transformed credential and determining that the transformed credential matches the challenge credential.
 17. The method of claim 11, further comprising: in response to determining that the client computer is a bot, performing one or more negative response actions.
 18. The method of claim 17 wherein the negative response action comprises generating an error code.
 19. The method of claim 17 wherein the negative response action comprises generating an error message.
 20. The method of claim 17 wherein the negative response action comprises sending a negative response to the client computer. 